In the land mobile radio (LMR) communication environment LMR networks conventionally use a single frequency range to transmit and receive radio signals. There exists many types of LMR networks using many transport and modulation schemes carrying different types of formatted information in the radio wave. The most basic are analog information and currently the most advanced are P25 & Tetra standards-based digital transmissions. LMR networks generally carry half duplex or multi channel duplex voice communications. Additionally, the digital based LMR networks are capable of carrying low bandwidth data.
Commercial wireless carrier networks use commercial frequency ranges to carry full duplex voice and packet data. The U.S. military makes use of other frequency areas in various low band and high band ranges carrying a variety of voice and data transmissions. The frequency ranges are separate from the public safety, government and commercial ranges so that the transmissions have minimal radio interference with each other. Additionally, multiple modulation schemes and transports exist between wireless carriers and vary greatly on military bands. Add to this the public broadband frequency allocations for 802.11 and other publicly available spectrum areas and the spectrum chart break down is fragmented in no particular order with a large number of incompatible modulation schemes and transports making it very difficult for specific voice and data applications using separate frequencies and networks to interoperate, as is illustrated in FIG. 1. FIG. 1 further illustrates GSM with SMS with full-duplex voice, UHF LMR analog with full channel voice with no transport layer, 800 MHz LMR P25 with narrow band voice, and military band for voice.
This stove piped frequency and transport arrangement has never been ideal but now there is an urgent need by the government and military with a compelling business case for commercial communication companies to be able to interoperate and communicate between frequencies and disparate networks using both existing and next generation equipment.